1. Field of the Invention
This invention relates generally to a dummy surface plate, more particularly relates to a dummy surface plate, which shields an insertion opening of housing. The housing is adapted to be used for storing a plurality of plate members inserted from the insertion opening so as to be arranged in parallel. Moreover, this invention relates to a housing which includes a dummy surface plate for shielding the insertion opening of the housing.
2. Description of Related Art
Conventionally, as a housing having an insertion opening, an electronic device housing such as a communication device, a computer, or a switching device is known. A plurality of printed boards as a plate member on which electronic components as an Integrated Circuit(IC) or a Large Scale Integration(LSI) are mounted, are inserted into or removed from the opening of the electronic device housing.
Generally, the rise in inside temperature of the electronic device housing occurs by the heat generated from the electronic components mounted on the printed board, which is stored in the electronic device housing. In order to prevent the rise in this temperature, a cooling fan is used for cooling the inside of the electronic device housing forcedly. In this case, a surface plate is attached to the opening so as to prevent the cooling air from leaking out to the outside of the electronic device housing.
Conventionally, the surface plate shown in FIG. 9 is known as an above-described surface plate. FIG. 9 shows a perspective view of a conventional dummy surface plate attached to a partial region of the opening of the electronic device housing.
As shown in FIG. 9, an electronic device housing 1 has an insertion opening 3. The insertion opening 3 allows insertion and removal of a plurality of printed boards in parallel with each other. In the following description, a part of the electronic device housing 1 where the insertion opening 3 is will be referred to also as a front part of the electronic device housing 1, and an opposite part of the electronic device housing 1 will be referred to also as a back part of the electronic device housing 1.
A back panel 4 is attached to the back part of the electronic device housing 1. A connector which is not shown is mounted on the back panel 4. A connector 6 is mounted on a printed board 2. When the printed board 2 was inserted into the insertion opening 3, the connector 6 is connected with the above-described connector mounted on the back panel 4. On the printed board 2, a plurality of electronic components, as the IC or LSI, are mounted. A panel is attached to a part of the electronic device housing 1 except for the front part and back part. An upper frame 7, as a first frame, and a lower frame 8, as a second frame, are formed in upper part and lower part of the insertion opening 3. The upper frame 7 and lower frame 8 are corresponding to an upper edge and lower edge of the printed board 2. The upper frame 7 has a plurality of grooves 9. The lower frame 8 has a plurality of grooves 11. The grooves 9 and grooves 11 are opposite each other in every slot. The upper edge (first edge) and lower edge (second edge) of the printed board 2 are guided slidably by the groove 9 and groove 11. The electronic device housing 1 has a plurality of upper grooves 12 inside, which guide the upper edge of the printed board 2 inserted into or removed from inside of the electronic device housing 1. Similarly, the electronic device housing 1 has a plurality of lower grooves which are not shown. The lower grooves guide the lower edge of the printed board 2 inserted into or removed from inside of the electronic device housing 1. The lower grooves correspond to the upper grooves 12 respectively. The printed board 2 has a surface plate 13 on a front edge, which is fixed by non-shown screws. The surface plate 13 shields the partial region of the insertion opening 3, in case the printed board 2 is inserted into the electronic device housing 1.
A grip lever 14 is fixed on upper end portion of the surface plate 13, and a grip lever 16 is fixed on lower end portion of the surface plate 13. The grip lever 14 has a construction which make the grip lever be a lock condition or an unti-lock condition. The lock condition is meant that the grip lever 14 is prevented itself to move relatively in direction between the front face and the rear face of the upper frame 7. The unti-lock condition is meant that the grip lever 14 is made itself be able to move relatively in direction between the front face and the rear face of the upper frame 7. The grip lever 16 has the same construction with the grip lever 14.
When the printed board 2 is inserted into the electronic device housing 1 through the partial region of the insertion opening 3, the grip lever 14 and 16 are in the unti-lock condition. After the printed board 2 is inserted into electronic device housing 1 and when the printed board 2 is stored inside of the electronic device housing 1, the grip lever 14 and 16 become being in the lock condition. The operation of inserting the printed board 2 into the electronic device housing 1 is done as descripted above. When the printed board 2 is removed from the electronic device housing 1 through the partial region of the insertion opening 3, the grip lever 14 and 16 are in the unti-lock condition. Such as the grip lever 14 and 16 are conventional construction, and descripted in Japanese patent applications, laid-open No. 9-18183.
In order to increase the cooling efficiency inside of the electronic device housing 1, it is needed that all region of the insertion opening 3 is shielded so that the cooling air inside of the electronic device housing 1 does not leak out to outside of the electronic device housing 1. For this reason, it is needed that the unused partial region of the insertion opening 3 is shielded. However, since the surface plate 13 and grip lever 14 and 16 shown as FIG. 9 are fixed to the printed board 2, the surface board 13 and grip lever 14 and 16 are conventionally fixed to a dummy printed board on which no electronic component is mounted in order to shield the unused slot.
In this case, since the number of parts for shielding the unused partial region of the insertion opening 3 is increased, the cost and the constructing work for the dummy printed board with the surface board 13, the grip lever 14 and 16 are increased. Moreover, it is necessary for the electronic device housing 1 to take electromagnetic shielding measures for preventing electromagnetic interference (EMI). As one of the measures, it is known that a plurality of metal springs for electromagnetic shielding are mounted on the each surface plate 13 so that each surface plate 13 is kept in pressure contact with each other.
However, though the conventional surface plate 13 as shown in FIG. 9 has the construction which prevents itself moving relatively in the front or the rear direction to the upper flame 7 and lower frame 8, it dose not have the construction which prevents itself moving in direction along the upper frame 7 and lower frame 8.
For this reason, when a plurality of printed boards 2 or dummy printed boards with the surface board 13, the grip lever 14 and 16 are inserted into the electronic device housing 1 through the insertion opening 3, the elastic power is generated from each metal spring. As the number of dummy printed boards with the surface board 13, the grip lever 14 and 16 or printed boards 2 increases, the total elastic power of each elastic power increases. In this case, each surface plate 13 moves in direction along the upper and lower frame 7 and 8. In this case, the conventional construction causes a reduction in working efficiency of an insertion or a removal of the dummy printed boards with the surface board 13, the grip lever 14 and 16 or the printed boards 2.